Circular Cylinder In Axial Flow

The boundary layer formed on the outer surface of a semi-infinite circular cylinder in steady axial incompressible flow is studied in this thesis. Governing equations are solved using local similarity techniques and a nonsimilar numerical approach.;Two obvious similarity transformations can be used to obtain solutions for this problem, but they do not yield the same results, since the flow is essentially nonsimilar. In the extreme case that the radius of the cylinder is much larger than the boundary layer thickness, only one of the transformation leads to the correct solution, i.e., the Blasius solution. The other transformation yields an axial velocity profile which is deceptively close to the Blasius. This is also strongly suggested by comparing the series expansions of axial velocity profiles from each transformation. Solutions obtained by using either transformation merge at downstream locations.;Since the use of a single similarity variable does not solve the problem in its full range, an overall numerical solution is obtained by applying Keller\u27s Box method with primitive variables and similarity coordinates. Similarity coordinates scale the axial and radial coordinates such that boundary layer growth does not appear explicitly as we move downstream. Thus, the numerical mesh does not need to be enlarged and this leads to increased efficiency in computation. Results are obtained in the range that start with the Blasius solution and proceed far downstream.;A local similarity method, which is very efficient, using primitive variables with similarity coordinates is also applied to obtain solutions that are valid over a wide range of the flow.;Results obtained by these methods compare well with previously obtained analytical and numerical solutions, but they extend considerably the range of solution

The value of acetazolamide single photon emission computed tomography scans in the preoperative evaluation of asymptomatic critical carotid stenosis

AbstractPurpose: Acetazolamide (ACZ)-enhanced single photon emission computed tomography (SPECT) scans can assess both cerebral perfusion and vascular reactivity. Patients with asymptomatic critical carotid artery stenosis were evaluated for cerebral vascular reactivity to determine the effect of extracranial occlusive disease and the effect of carotid endarterectomy (CEA) on intracerebral reactivity. Methods: In 44 patients with asymptomatic critical carotid artery stenosis, cerebral perfusion and vascular reactivity were assessed before CEA with resting and ACZ-enhanced SPECT scans. All patients had a 70% or greater ipsilateral internal carotid artery stenosis. Preoperative ACZ-enhanced SPECT scans were obtained, usually 5 days before CEA. Postoperative ACZ-enhanced SPECT scans were obtained in 30 patients. Results: Preoperative SPECT scans were asymmetric, revealing focal (n = 19) or global (n = 15) decreased reactivity in 34 patients (77%). Ten patients had symmetric or normal reactivity. After CEA, 23 patients demonstrated an improvement in reactivity ipsilateral to the side of surgery. The remaining seven patients failed to improve after surgery. Conclusion: Although all patients had a high-grade internal carotid stenosis, nearly a quarter of the patients had excellent intracerebral collateral flow. Only 71% of patients demonstrated improved intracerebral vasoreactivity after CEA. The lack of improvement in the other patients may have resulted from intracerebral pathology or lack of improvement in the extracranial carotid hemodynamics. (J Vasc Surg 1999;30:599-605.

Monarchy and Constructing Identity in 'British' Gibraltar, c.1800 to the Present.

British Gibraltar began as a fortress, and royal coronations, jubilees and visits were initially celebrated in Gibraltar primarily by the British military and the colonial government. However, a substantial civilian population developed, to service the garrison and engage in trade. Sections of this civil community, not British-by-birth, increasingly demonstrated their loyalty to the crown on such royal occasions, in order to raise their status internally, protect their interests and increase their political influence inside Gibraltar. Spanish participation in royal events in Gibraltar, especially by members of the military and political elites from across the frontier, were also once commonplace and in Gibraltar uncontested. However, the relationship with Spain deteriorated, especially from the 1950s. Gibraltar's civil community then used expressions of loyalty to the British crown on royal occasions to assert its Britishness and to emphasise the duty of the British government to resist Spanish claims

Body Invaders : Panic Sex in America

"Body Invaders is a critical collection of thematically focussed essays dealing with the fate of the body in the postmodern condition. Beginning with a comprehensive and original set of theses on contemporary America ("Panic Sex in America"), Body Invaders also includes key theme section theorising the fate of the postmodern body from the perspectives of fashion, art, and popular culture." -- p. [4] of cover